I took translucent square beads of different colors 5mm in size, strung on long, at least 2cm (otherwise, fall out) cloves.
I took a wire 1.5mm 9cm long, attached on one side to the holder for the keychain.
On the other hand, as can be seen from the photo - made a loop with pliers so that the ball does not fall off the mount.
Here is such a ball! Weight is already 120 grams! I don’t know how he will stay on the Christmas tree, but even just as a souvenir he will decorate the house.